+Bohr Models and Isotopes 01/22Agenda:1.Calculating protons,

neutrons, and electrons warm up

2.Calculation practice3.Bohr models4.Atomic brother

Please pick up the handout on the front table and begin filling in the front side key and atom

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Atomic Structure PracticeBohr ModelsValence ElectronsIdentifying Elements

+Let’s Review…

What was Bohr’s contribution to our understanding of atomic structure?

What does a Bohr model look like? How do we determine the number of protons in an

atom of an element? How do we determine the number of electrons in an

atom of an element? How do we determine the number of neutrons in an

atom of an element?

+Let’s Review…What was Bohr’s contribution to our understanding of atomic structure?

+Let’s Review…

Orbiting electrons Energy levels

What was Bohr’s contribution to our understanding of atomic structure?

+Let’s Review…What does a Bohr model look like?

+Let’s Review…What does a Bohr model look like?

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+Let’s Review…What does a Bohr model look like?

+Let’s Review…How do we determine the number of protons in an atom of an element?

+Let’s Review…How do we determine the number of protons in an atom of an element?

3

LiLithium

7

Protons = 3

+Let’s Review…How do we determine the number of electrons in an atom of an element?

+Let’s Review…How do we determine the number of electrons in an atom of an element?

3

LiLithium

7

Protons = 3

Electrons =3

+Let’s Review…How do we determine the number of neutrons in an atom of an element?

+Let’s Review…How do we determine the number of neutrons in an atom of an element?

Atomic mass – Atomic Number

7 – 3 = 4 neutrons

3

LiLithium

7

Protons = 3

Atomic mass = 7

+Bohr Model PracticeCreate models of atoms of the elements assigned by your teacher using your periodic table for reference.

+Valence Electrons

Reactivity: filling the outer energy level

Images: www.cyberlepsy.com and www.teachervision.com

Valence electrons determine the chemical properties of an element.

+Isotopes, Ions and Valence Electrons

+Isotope Atoms of the same element with

different numbers of neutrons in the nucleus.

Causes a different atomic mass. Example:

Taken from: http://www.emc.maricopa.edu/faculty/farabee/biobk/cisotopes.gif

+Isotope

Question: What changes when you add or take away a neutron from an atom?

Answer: The atomic mass changes: it increases when a atom has an extra neutron, and decreases when it has one less neutron.

+IsotopeQuestion: Which of the atoms below are

isotopes for Sodium-12? Hint: Use your periodic table to make calculations and

compare.

Answer: Sodium’s atomic # is 11, so it has 11 protons and 11 electrons. Choice C has 13 neutrons compared to Sodium-12, so it gained a neutron.

Choice: Element Protons Neutrons Electrons

A. Na 11 12 12B. Na 12 12 11C. Na 11 13 11

+Ion Atoms that have lost or gained

electrons. Causes a different electric charge

(positive or negative) Example:

Click here for animations describing this further.

Taken from: http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20101/bio%20101%20lectures/chemistry/chemistr.htm

+Ion

Question: What changes when you add an electron to an atom?

Answer: The electric charge changes to become negatively charged.

(Since electrons are negatively charged, adding an electron will cause the atom to be negatively charged.)

+Ion

Question: What changes when you take away an electron to an atom?

Answer: The electric charge changes to become positively charged.

(Since electrons are negatively charged, taking away an electron will cause the atom to be positively charged.)

+IonQuestion: Which of the atoms below are

ions? Hint: Use your periodic table to make calculations and

compare.

Answer: Oxygen’s atomic number is 8, so a neutral atom would have 8 protons and 8 electrons. Choice A has 9 electrons, making it an ion.

Bonus questions:- Is this ion negatively or positively charged?- Which answer choice shows an isotope?

Choice: Element Protons Neutrons Electrons

A. O 8 8 9B. O 9 8 8C. O 8 7 8

+Valence ElectronsElectrons in the outermost energy level

of an atom that determine the element’s chemical properties.

For Elements #1 – 30, there can be 8 valence electrons in the outer shell

Taken from: http://hyperphysics.phy-astr.gsu.edu/hbase/solids/sili.html

+Valence Electrons If an element is stable, it has all 8 valence

electrons. Elements with less than 8 valence electrons are

reactive.

Taken from: http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20101/bio%20101%20lectures/chemistry/chemistr.htm

For example, Sodium, which has 1 valence electron, reacts with Chlorine, which has 7.

When the atoms combine, they have a total of 8 valence electrons (1 + 7 = 8)

NaCl is a stable molecule, but Na and Cl on their own are reactive.

+Valence Electrons The periodic table is organized with similar

valence electrons in the same columns.

Taken from: http://cactus.dixie.edu/smblack/chem1010/lecture_notes/3A.htm

Which columns would react?

Which are stable?

Can you predict which will react with each other?

+Valence Electrons

Question: Where are the valence electrons located?

Answer: Valence electrons are located in the outer shell.

+Valence ElectronsQuestion: How many valence electrons need to

be in the outer shell for it to be stable?

Answer: 8

+Valence ElectronsQuestion: Which of the atoms would react

with each other? Hint: Use your periodic table for help. Notice the Roman

Numerals above each column tell you the number of valence electrons: I = 1, II = 2, III = 3, IV = 4, V = 5, VI = 6, VII = 7, VIII = 8.

Hydrogen Helium Argon

Aluminum Bromine Calcium

Answer: Hydrogen and Bromine would react. Hydrogen is in column 1, so it has 1 valence electron. Bromine is in column 7, so it has 7 electrons. 1 + 7 = 8!

+Reactivity & Valence ElectronsVIDEO: The Reaction Between Water and the First Group Elements

Group 1: Alkali MetalsLithium, Sodium, Potassium, Rubidium, Cesium, Francium

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Let’s look at their atomic structure.

Sodium

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Let’s look at their atomic structure.

Potassium

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Let’s look at their atomic structure.

Cesium